Choice B is the correct answer. Let's rearrange the first equation.

Step 1: From $y = -x + 7$: $x + y = 7$

Multiply by 2: $2x + 2y = 14$

This is exactly the second equation!

Conclusion: Infinitely many solutions (same line)

💡 Strategic Tip: Don't be fooled by different forms—convert to the same form to compare.

Choice A is incorrect because no solution requires parallel lines with different constants.

Choice C is incorrect because one solution requires different slopes.

Choice D is incorrect because linear systems cannot have exactly three solutions.